Add hardware interrupt notification mechanism

This allows privileged userland drivers to get notifications of hardware
interrupts.

Initial work by Zheng Da, reworked by Damien Zammit and myself.

* Makefrag.am (libkernel_a_SOURCES): Add device/intr.c and
device/intr.h.
(include_device_HEADERS): Add include/device/notify.defs and
include/device/notify.h.
* device/dev_hdr.h (name_equal): Add declaration.
* device/ds_routines.c: Include <device/intr.h>
(ds_device_intr_register, ds_device_intr_ack): New functions.
* device/intr.c, device/intr.h: New files.
* doc/mach.texi (Device Interrupt): New section.
* i386/Makefrag.am (libkernel_a_SOURCES): Add i386/i386/irq.c and
i386/i386/irq.h.
* i386/i386/irq.c, i386/i386/irq.h: New files.
* i386/i386at/conf.c: Include <device/intr.h>.
(irqname): New macro.
(dev_name_list): Add irq device.
* include/device/device.defs (device_intr_register, device_intr_ack):
New RPCs.
* include/device/notify.defs, include/device/notify.h: New files.
* kern/startup.c: Include <device/intr.h>
(start_kernel_threads): Start intr_thread thread.
* linux/dev/arch/i386/kernel/irq.c: Include <device/intr.h>
(linux_action): Add user_intr field.
(linux_intr): Call user_intr action if any.
(mask_irq, unmask_irq): Move functions to i386/i386/pic.c
(__disable_irq, __enable_irq): Move functions to i386/i386/irq.c.
(install_user_intr_handler): New function.
(request_irq): Initialize user_intr field.
* linux/src/include/asm-i386/irq.h (__disable_irq, __enable_irq): Remove
prototypes.
* i386/i386/pic.c (mask_irq, unmask_irq): New functions.
* i386/i386/pic.h (mask_irq, unmask_irq): New prototypes.

6 files changed, 177 insertions, 0 deletions

diff --git a/i386/Makefrag.am b/i386/Makefrag.am
index f38c0785..59571416 100644
--- a/i386/Makefrag.am
+++ b/i386/Makefrag.am
@@ -102,6 +102,8 @@ libkernel_a_SOURCES += \
 	i386/i386/io_perm.c \
 	i386/i386/io_perm.h \
 	i386/i386/ipl.h \
+	i386/i386/irq.c \
+	i386/i386/irq.h \
 	i386/i386/ktss.c \
 	i386/i386/ktss.h \
 	i386/i386/kttd_interface.c \
diff --git a/i386/i386/irq.c b/i386/i386/irq.c
new file mode 100644
index 00000000..c65d2ea2
--- /dev/null
+++ b/i386/i386/irq.c
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 1995 Shantanu Goel
+ * Copyright (C) 2020 Free Software Foundation, Inc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <i386/irq.h>
+#include <device/intr.h>
+#include <mach/kern_return.h>
+#include <kern/queue.h>
+#include <machine/machspl.h>
+
+extern queue_head_t main_intr_queue;
+
+static void
+irq_eoi (struct irqdev *dev, int id)
+{
+  /* TODO EOI(dev->irq[id]) */
+}
+
+static unsigned int ndisabled_irq[NINTR];
+
+void
+__disable_irq (irq_t irq_nr)
+{
+  assert (irq_nr < NINTR);
+
+  spl_t s = splhigh();
+  ndisabled_irq[irq_nr]++;
+  assert (ndisabled_irq[irq_nr] > 0);
+  if (ndisabled_irq[irq_nr] == 1)
+    mask_irq (irq_nr);
+  splx(s);
+}
+
+void
+__enable_irq (irq_t irq_nr)
+{
+  assert (irq_nr < NINTR);
+
+  spl_t s = splhigh();
+  assert (ndisabled_irq[irq_nr] > 0);
+  ndisabled_irq[irq_nr]--;
+  if (ndisabled_irq[irq_nr] == 0)
+    unmask_irq (irq_nr);
+  splx(s);
+}
+
+struct irqdev irqtab = {
+  "irq", irq_eoi, &main_intr_queue, 0,
+  {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
+};
+
diff --git a/i386/i386/irq.h b/i386/i386/irq.h
new file mode 100644
index 00000000..d48a8e92
--- /dev/null
+++ b/i386/i386/irq.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2020 Free Software Foundation, Inc.
+ *
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ *
+ * THE FREE SOFTWARE FOUNDATION ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  THE FREE SOFTWARE FOUNDATION DISCLAIMS ANY LIABILITY OF ANY KIND
+ * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ */
+
+#ifndef _I386_IRQ_H
+#define _I386_IRQ_H
+
+#include <i386/pic.h>
+
+typedef unsigned int irq_t;
+
+void __enable_irq (irq_t irq);
+void __disable_irq (irq_t irq);
+
+extern struct irqdev irqtab;
+
+#endif
diff --git a/i386/i386/pic.c b/i386/i386/pic.c
index 0feebc6f..62ed9ed1 100644
--- a/i386/i386/pic.c
+++ b/i386/i386/pic.c
@@ -49,6 +49,24 @@ OTHER TORTIOUS ACTION, ARISING OUR OF OR IN CONNECTION
 WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
+/*
+ * Copyright (C) 1995 Shantanu Goel.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
 #include <sys/types.h>
 #include <kern/printf.h>
 #include <i386/ipl.h>
@@ -185,3 +203,57 @@ intnull(int unit_dev)
 	}
 
 }
+
+/*
+ * Mask a PIC IRQ.
+ */
+inline void
+mask_irq (unsigned int irq_nr)
+{
+	int new_pic_mask = curr_pic_mask | 1 << irq_nr;
+
+	if (curr_pic_mask != new_pic_mask)
+	{
+		curr_pic_mask = new_pic_mask;
+		if (irq_nr < 8)
+		{
+			outb (PIC_MASTER_OCW, curr_pic_mask & 0xff);
+		}
+		else
+		{
+			outb (PIC_SLAVE_OCW, curr_pic_mask >> 8);
+		}
+	}
+}
+
+/*
+ * Unmask a PIC IRQ.
+ */
+inline void
+unmask_irq (unsigned int irq_nr)
+{
+	int mask;
+	int new_pic_mask;
+
+	mask = 1 << irq_nr;
+	if (irq_nr >= 8)
+	{
+		mask |= 1 << 2;
+	}
+
+	new_pic_mask = curr_pic_mask & ~mask;
+
+	if (curr_pic_mask != new_pic_mask)
+	{
+		curr_pic_mask = new_pic_mask;
+		if (irq_nr < 8)
+		{
+			outb (PIC_MASTER_OCW, curr_pic_mask & 0xff);
+		}
+		else
+		{
+			outb (PIC_SLAVE_OCW, curr_pic_mask >> 8);
+		}
+	}
+}
+
diff --git a/i386/i386/pic.h b/i386/i386/pic.h
index f492de5e..6434bf08 100644
--- a/i386/i386/pic.h
+++ b/i386/i386/pic.h
@@ -180,6 +180,8 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 extern void picinit (void);
 extern int curr_pic_mask;
 extern void intnull(int unit);
+extern inline void mask_irq (unsigned int irq_nr);
+extern inline void unmask_irq (unsigned int irq_nr);
 #endif /* __ASSEMBLER__ */
 
 #endif	/* _I386_PIC_H_ */
diff --git a/i386/i386at/conf.c b/i386/i386at/conf.c
index fe7c7c09..ca5d0dfb 100644
--- a/i386/i386at/conf.c
+++ b/i386/i386at/conf.c
@@ -68,6 +68,9 @@
 #define hypcnname		"hyp"
 #endif	/* MACH_HYP */
 
+#include <device/intr.h>
+#define irqname			"irq"
+
 /*
  * List of devices - console must be at slot 0
  */
@@ -149,6 +152,11 @@ struct dev_ops	dev_name_list[] =
 	  nodev },
 #endif	/* MACH_HYP */
 
+        { irqname,      nulldev_open,   nulldev_close,    nulldev_read,
+          nulldev_write,nulldev_getstat,nulldev_setstat,  nomap,
+          nodev,        nulldev,        nulldev_portdeath,0,
+          nodev },
+
 };
 int	dev_name_count = sizeof(dev_name_list)/sizeof(dev_name_list[0]);